Lowering device in molding machines



April 25, 1933 G. zlMMERMANN LOWERING DEVICE IN MOLDING MACHINES Filed March 3, 1931 2 Sheets-Sheet 1 April 25, 1933.

G. ZIMMERMANN LOWERING DEVICE IN MOLDNG MACHINES 2 Sheets-Sheet 2 Filed March 3, 1931 Fey. 3

Patented Apr. 25, 1933 UNITED STATES PATENT oFFlcE GUs'rAV zrnrrnaivmnn, or nussnnnonnennivmnr LOWERING'DEVICE IN Iii/.CO131311911?l MACHINES Application filed. March 3, 1931, Serial 110.519,90), and in Germany .Tune 4, 1930.

The present invention relates to a lowering device in molding machines for foundries and ceramic operations.

It is well known to remove the model of an article to be. produced by the casting process from its embedding in the casting mold, in that, for example, in the case of a model located at the bottom this is withdrawn downwardly from the stationary disposed mold. This method of separating the model from the casting mold is referred to as lowering. In order to regulate the speed of this lowering operation, there is used amongst other things the arrangement that 5 during the lowering a liquid, such1 as water,

oil or the like must be removed. The resistance offered by the passages and openings to the movement of the liquid iiowing through them influences the movement of a piston which displaces it and thus the speed at which the model moves out of the mold. According as to whether the said passages are dimensioned or opened more or less wide, the lowering movement will be faster or slower.

The invention relates to a particularly advantageous lowering arrangement, generally called hydraulic lowering, which operates entirely without shock. In pressure molding machines, according to the invention, the pressure piston is simultaneously used as a part of the lowering device. When used in connection with turnover'molding machines it affords the advantage that itcompletely prevents the much feared escape of oil from the lowering cylinder, in that the liquid in both turning positions is kept in containers through the bottom of which there does not pass any movable rod. Moreover, the connection of the lowering device with the pressure device involves heavy loading of this side of the machine and relieving of the load on the opposite side which has already a higher weight by reason of the shaking device. The result of the new arrangement is that the center of gravity of the machine is displaced towards the middle of the rotary arm, whereby pits in the ground are obviated.

By way of example, a turnover molding machine with liquid lowering is illustrated in the accompanying drawings ina `which Figure 1 is a front view of the machine, withl the pressure vand 4lowering device in section; Fig. 2, a side view thereof; Fig. 3, 53 a sectional view of the lowering device, of the machine in the completed pressure position; Fig. 4, a front view of the turned machine, partly in section; Fig. 5, a. view of the lower portion of this machine in the C3 lowered position; Fig. 6,y a cross section of a regulating member; Fig. 7, a vertical section ofthe pressure and lowering device; andFig. 8, a top view of this device. v

Referring to the drawings, in a frame 1 a shaft 2 is rotatably mounted carrying an arm 3, tol one end of which a cylinder 4 is secured carrying a molding table 5 which may be caused to carry out a shaking movement by a shaking device of known type 7.0 mounted in the cylinder 4.

`The other end ofthe arm 3 carries a double cylinder 6, 7.. Inv the cylinder 6` there is. movable in a Huid-tight manner a piston 8 and in the cylinder 7, a plunger 9, 7J both pistons being united in a disc 11. Into the part 10 of the plunger 9 is screwed the supporting rod 12 of a plate 13.v The hollow space 14 ofthe piston 8 serves for the reception of the liquid, kas a rule oil, see 90. Fig.'3.

The piston 9 is of conical formation at its end and provided with a bore 15 which connectsu the space 30 shut oif by the plunger 9 with the space 14 shut off by the piston 8. 85 These spaces are connected also by the conduits 17, 17 which unite in a casing 32 attached to the cylinders 6, 7 and which are in communication or separated from one another according to the position of the rotary slide 16 moved by the rods 18, 18. Through a pipe 19 arranged in a fluid-tight manner in the connecting wall of the cylinders 6, 7 compressed air can be conducted into the space 14, the pipe 19 serving also for the 95 outflow of the air. The closing device required for this double function ofthe pipe 19 may, for example, consist of a three-way cock, not shown, which in one position connects the pipe 19` with a compressed air piping, in its other position, however, with the atmosphere, and in the third position closes it completely.

The length to which the pipe 19 projects into the cylinder 6 is so dimensioned that no liquid can enter the pipe.

According to Fig. 6, the rotary slide 16 has a larger passage 21l and asmaller one, 20. When the slide is turned so that the bore 20 is adjusted to iow, liquid can pass ronly very slowly from one space into. the

other. Further turning of the slide 16 will bring into play the passage 21 and thus increase the amount of liquid that can pass.

To the cylinder 6 the auxiliary cylinders 27 are secured, and their pistons 25 with the rods 26 and the arms 29 attached to the disc 11 can displace the double piston 8, 9. The compressed air required v.for this purpose is introduced into the cylinders 27 through the pipes 28.

W'hen a kmodel is tobe molded, the machine is in the position shown in Figs. 1, 2, 3 and 7. After the mold boxV on the table 5 has been filled sufficiently with mold mass, compressed air is supplied through the pipe 19. The air fills the space 14 and enters also the space above the piston 9 through the bores 15 and 17 so that the pistons 8. 9 with the pressure plate 13 are pressed downwardly whereby the molding mass is compressed in the known manner.y The necessary-model as well as the molding box and the known further equipment are not' shown. rlhis end position is illustrated in Fig. 3.

By turning the arm 3 through 180 the positionshown in Fig. 4 isreached. The

liquid 'contained in the space 14 has sunkdown into the space 31. When the slide 16 is opened, it passes also into the space 30 by' pressing out the air contained therein through the bore 15. If the slide 16 is now closed and the pipe 19 connected to the atmosphere, the pistons 8, 9 can descend only to an extent corresponding tothe passage of liquid through the relatively narrow bore 15. The molding box clamped to the plate 13 is thus withdrawn very slowly and without the least shock from the model attached to the table 5. l

If the lowering is to take place more rapidly in cases where, for example, the mold has separated already from the model, the rotary slide 16 is adjusted so that its passage opening is released and the liquid can quickly pass from the space 30 into .the space 14. The end-position is shown in Fig. 5, and when it is reached, the molding box can be lifted off. Then the arm 3 is turned again 180 while the pipes 17 and 19 are closed, whereby the position according to Figs 1 and 2 is attained again. i

In order to hold the pressure plate 13 safely in its uppermost position and to raise and Vlower it independently of the rotary motion of the arm, the auxiliary cylinders 27 with the compressed air pipings 28 are provided.

The lowering device can be employed also where the lowering piston is not to be used as pressure piston. 'Ihe pipe 19' can then be closed by a simple cock which in its open position connects thepipe with the atmosphere.

Instead of the stationary cylinder with movable'pistons it is also possible to use stationary pistons with movable cylinders. If it should be necessary, the passage through the bores 15 or through a pipe replacing them may be provided with a regulating member in order to vary the cross section of the passage.

1. In a molding machine asupporting element, means byV which said element isV mounted for angular movement in a vertical plane, a molding table at one end of ing the inner ends of the cylinders, a valve to control the passage of liquid through said duct from one cylinder to the other, means to supplymotor fluid under pressure to the'second named cylinder to impart outi stroke to both of the pistons when the cylinders and pistons are in raised position, a pressure plate secured to and movable by the piston and means independent of the cylinders to impart instroke to the pistons.

2. A molding machine as claimed in claim 1, in which the cylinder in which the chamber piston operates is of greater diameter than the other and in which the means for supplying motor fluid to said larger cylinder comprises a tube which extends into the inner end portion of said larger cylinder and `is so arranged as to enter the chamber of the larger piston when the pistons are in instroke position.

3. A molding machine as claimed in claim 1, in which the plate which is connected to the pistons has a screw stem which engages a threaded bore in the outer end portion of the piston which has the restricted duct.

In testimony whereof I have afiixed my signature.

. GUSTAV ZIMMERMANN. 

